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From knowing by name to targeting: the meaning of identification under the GDPR

From knowing by name to targeting: the
meaning of identification under the GDPR
Nadezhda Purtova*
Identification, referring both to the process of identify-
ing someone and the fact of being identified, is one of
the boundary concepts of data protection law. It sepa-
rates the data that is personal, i.e. relating to an identi-
fied or identifiable natural person, from non-personal,
and thus triggers the applicability of the EU General
Data Protection Regulation (the GDPR).
Yet, despite
the high stakes attached to the meaning of this concept,
relatively little attention is paid both in law and legal
scholarship to what identification is. Therefore the chief
issue tackled here is the meaning of identification under
the GDPR.
Key Points
Despite its core role in the EU system of data
protection, the meaning of identification remains
unclear in data protection law and scholarship
while the spotlight focuses on the legally relevant
chance of identification, ie identifiability.
While Article 29 Working Party interpreted iden-
tification broadly, as distinguishing one in a
group, this interpretation has been questioned in
light of the CJEU decision in Breyer. This article
tackles this uncertainty.
This article offers an integrated socio-technical
typology of identification where, in addition to
the known identification types (look-up-, recog-
nition-, session- and classification identification),
targeting is added as a new identification type.
To identify by way of targeting means to select a
particular individual from a group as an object of
attention or treatment in a single moment of
The article clarifies the legal meaning of identifi-
cation under the GDPR. It proposes a contextual
interpretation of Breyer, which negates Breyer’s
restrictive potential and brings all identification
types within the GDPR.
The article concludes with a discussion of the
implications of this reading of identification for
data protection in terms the applicability of the
GDPR to new data technologies and practices
such as facial detection and non-tracking based
targeted advertising, effects of certain privacy
preserving technologies such as federated learn-
ing of cohorts, consequences for invoking data
protection rights when identification is not possi-
ble, but also in terms of the need to clearly define
the objectives of the data protection law.
*Nadezhda Purtova, Faculty of Law, Economics, and Governance, Utrecht
University, Utrecht, the Netherlands.
This contribution reports on the results of the project ‘Understanding infor-
mation for legal protection of people against information-induced harms’
(‘INFO-LEG’). This project has received funding from the European Research
Council (ERC) under the European Union’s Horizon 2020 research and inno-
vation programme (grant agreement No 716971). The article reflects only the
author’s view and the ERC is not responsible for any use that may be made of
the information it contains. The funding source had no involvement in study
design, in the collection, analysis and interpretation of data, in the writing of
the report, and in the decision to submit the article for publication. I am espe-
cially grateful to Dr Michael Veale for his sharp comments and suggestions. I
thank the journal editors Dr Jaap-Henk Hoopman, Dr Raphael Gellert, Prof.
Ronald Leenes and the anonymous reviewer of this article for helping me
sharpen this article’s analysis.
1 Regulation (EU) 2016/679 of the European Parliament and of the
Council of 27 April 2016 on the protection of natural persons with regard
to the processing of personal data and on the free movement of such
data, and repealing Directive 95/46/EC (General Data Protection
Regulation), OJ 2016 L 119/1.
2 The legal order of the Council of Europe, specifically Council of Europe
Convention no 108 for the protection of individuals with regard to auto-
matic processing of personal data of 28 January 1981, as updated in 2018
(‘Convention 108þ’) also operates with the concept ‘personal data’ and
defines it through the concept of identification as ‘any information relat-
ing to an identified or identifiable individual’ (Art 2(a) Convention
108þ). Yet, examining the meaning of identification in the legal order of
the Council of Europe is beyond scope of this article. It suffices to note
that the European Court of Human Rights in its case law on Article 8
right to respect for private life referred to Convention 108þand the defi-
nition of personal data, and recognized that ‘[s]uch data cover not only
information directly identifying an individual ..., such as surname and
forename, ...but also any element indirectly identifying a person such as
a dynamic IP (Internet Protocol) address’ (Registry of the European
CThe Author(s) 2022. Published by Oxford University Press.
This is an Open Access article distributed under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs licence (https://creativecom-, which permits non-commercial reproduction and distribution of the work, in any medium, provided the original work is
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International Data Privacy Law, 2022, Vol. 12, No. 3 163
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The primary focus of the current scholarly attention
lies on the adjacent concept of identifiability which
refers to the possibility of identification, ie of being iden-
tified, in future.
This is not surprising since in practice
whether or not a person is identifiable rather than iden-
tified is regarded as an easier criterion to meet and is
therefore a de facto ‘threshold condition’ when deter-
mining the status of data as personal.
Some legal schol-
ars discuss the meaning and legally relevant degree of
pseudonymization, and true meaning
and possibility of anonymization.
The debates among
computer scientists tackle anonymization and reidenti-
fication techniques and their (in)effectiveness.
discussions clarify the boundaries of application of data
protection law and contribute to practical solutions for
at least some of the data protection concerns, and as
such are valuable and relevant. Yet, the meaning of
identifiability is derived from and hence is secondary in
relation to the primary concept of identification.
Therefore any identifiability debate is at risk of being
hollow when not underpinned with a robust under-
standing of identification. It makes little sense to argue
if a natural person is ‘identifiable’ when it is not clear
when a natural person would be ‘identified’ and what it
means to identify somebody.
As the technologies to target a person evolve and test
the boundaries of data protection, the meaning of iden-
tification becomes less clear, and the gap in understand-
ing what it means to identify becomes increasingly more
obvious and imperative to close.
A relatively recent
case of such technological development is face detection
and analysis used in ‘smart’ advertising boards.
with facial recognition where one’s facial features are
compared to pre-existing facial templates to establish if
a person is known, face detection and analysis do not
recognize people but ‘detect’ them and, in case of smart
billboards, classify them into gender-, age-, emotion-,
and other groups based on processing of their facial fea-
tures to display tailored ads. The industry that develops,
sells, and employs the technology argues that facial de-
tection does not involve processing personal data,
because the chance of establishing who a person before
the ‘sensor’ is close to null. In part this is due to the
‘transient’ nature of the processing, where raw data of
an individual processed by the detection ‘sensors’ is dis-
carded immediately.
The technology does not allow
tracking a person and recognizing him or her over time
either. To be clear, as will become apparent from further
analysis, these industry arguments do not necessarily
withstand legal scrutiny and it is highly likely that per-
sonal data will be processed in these contexts, if the pro-
posed interpretation of identification is adopted. Yet,
there is no uniform position on the interaction of face
detection and data protection across the EU Member
For instance, the Dutch data protection au-
thority considers face detection in the context of smart
billboards as processing of personal data,
while its
Irish and reportedly Bavarian counterparts are of the
opposite view.
More similar debates and uncertainties
are likely to emerge in other contexts where facial
Court of Human rights, Guide to the Case-Law of the of the European
Court of Human Rights. Data protection, updated on 31 December 2021
c>accessed 28 February 2022, analysis on page 7 and the cited case law).
A brief study of the relevant case law suggests that the ECHR analysis
also does not specifically address the meaning of identification as op-
posed to identifiability.
3 Article 29 Working Party ‘Opinion 4/2007 on the concept of personal
data’ (WP 136, 20 June 2007), 12.
4 WP136, 12.
5 Frederic J Zuiderveen Borgesius, ‘Singling Out People Without Knowing
Their Names Behavioural Targeting, Pseudonymous Data, and the New
Data Protection Regulation’ (2016) 32 Computer Law & Security Review
256; Paul Schwartz and Daniel Solove, ‘The PII Problem: Privacy and a
New Concept of Personally Identifiable Information’ (2011) 86 NYU L
Rev 1814, 1877.
6 Eg M Finck and F Pallas, ‘They Who Must Not Be Identified—
Distinguishing Personal From Non-Personal Data Under the GDPR’
(2020) 10(1) IDPL 11.
7 Among most notable, Arvind Narayanan and Vitaly Shmatikov, ‘Myths
and Fallacies of “personally Identifiable Information”’ (2010) 53(6)
Communications of the ACM 24; Sweeney on k-anonymity (eg Latanya
Sweeney, ‘k-Anonymity: A Model for Protecting Privacy’ (2002) 10(5)
International Journal on Uncertainty, Fuzziness, and Knowledge-Based
Systems 557) and responses to it, eg the works of Dwork and others on
differential privacy, eg Cynthia Dwork and Aaron Roth, ‘The
Algorithmic Foundations of Differential Privacy’ (2014) 9(3–4)
Foundations and Trends in Theoretical Computer Science 211–407
24 July 2020.
8 Nadezhda Purtova, ‘The Law of Everything. Broad Concept of Personal
Data and Future of EU Data Protection Law’ (2018) 10(1) Law,
Innovation, and Technology 40, 74; Peter Davis, ‘Facial Detection and
Smart Billboards: Analysing the “Identified” Criterion of Personal Data
in the GDPR’ (2020) 1 University of Oslo Faculty of Law Legal Studies
Research Paper Series, <>accessed 27
July 2020.
9 Ibid.
10 Fraunhofer Institute for Integrated Circuits IIS, ‘Emotion Recognition
Software SHORE
: Fast, Reliable and Real-time Capable’, <https://www.
tion.html>accessed 24 July 2020.
11 Damian George, Kento Reutimann and Aurelia Tamo` -Larrieux, ‘GDPR
Bypass by Design? Transient Processing of Data under the GDPR’ (2019)
9(4) International Data Privacy Law 285, 286.
12 As demonstrated by Davis (n 8).
13 Autoriteit Persoonsgegevens ‘Normenkader Digitale Billboards’
(‘Normative Framework for Digital Bilboards’) (25 June 2018) <https://
branche_normkader_digitale_billboards.pdf>accessed 19 February 2021.
14 Data Protection Commissioner, ‘Press Release on the Use of Facial
Detection Technology in Advertising’ (15 May 2017) <www.dataprotec
Technology-in-Advertising/i/1634.htm>accessed 17 February 2018, no
longer available; on hand with the author. The report published on 8
June 2017 by the Bavarian Data Protection Authority for the Private
164 ARTICLE International Data Privacy Law, 2022, Vol. 12, No. 3
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analysis and sensing can be used, such as healthcare for
pain or pulse detection, in the news sector for audience
measurement, or in assisted driving,
video surveillance
with face analytics,
but also online in the context of
tracking-free advertising,
and in other cases of the
‘transient’ data processing. While the applicability of
the GDPR would be the focus of debate in these con-
texts, the discussions will inevitably emerge also where
the applicability of the GDPR is not in dispute, eg in the
context of invoking data protection rights. Article 11(2)
GDPR—under some caveats—exempts data controllers
from complying with data subjects’ data access and rec-
tification requests, requests for erasure and restriction
of processing, as well as data portability obligations
where ‘the controller is able to demonstrate that it is not
in a position to identify the data subject’. The question
will then be: what does it mean to identify? The defini-
tion of biometric data in Article 4(14) GDPR and pseu-
donymization in Article 4(5) GDPR also hinge on the
meaning of identification.
To date, there have been disappointingly few
attempts in the data protection legal scholarship, at least
in English, at understanding identification beyond iden-
tifiability. In 2007 Leenes proposed a four-fold classifi-
cation of identification. According to Leenes, there is
more to identification than simply establishing one’s
civil identity, and we need to read identification broadly
if we are to address the ‘real privacy concerns’.
He dis-
tinguished look-up (l-), recognition (r-), classification
(c-), and session (s-) identifiability.
A recent notable
contribution to the debate on the meaning of identifica-
tion is by Davis who examines the meaning of an ‘iden-
tified natural person’ specifically in the context of smart
billboards and articulates the importance of looking
into the meaning of ‘identified’ as a baseline for estab-
lishing the meaning of ‘identifiable’.
However, Leenes,
while examining the meaning of identification in data
protection law, does so with a view to inform the
information privacy debate across borders rather than
to offer an interpretation of the specific legal concept of
the EU data protection law, among others in light of the
evolving case law of the Luxemburg Court, and Davis’
analysis is limited to the legal status of data in the con-
text of facial detection. Jasserand addressed the meaning
of identification under the GDPR framework, but only
when it concerns the definition of biometric data.
In addition, there is a swirling stream of sociological
and philosophical literature focusing on the related con-
cepts of identity and anonymity. To name a few, in
1999 Gary Marx presented a sociological typology of
what he called ‘identity knowledge’, which is the oppo-
site of anonymity and hence I consider it equal to iden-
tification. He specified seven broad types of identity
knowledge: legal name, locatability, pseudonyms linked
to identity or location, pseudonyms that are not linked
to name or location, pattern knowledge, social categori-
zation, and symbols of eligibility/non-eligibility.
Helen Nissenbaum discussed the meaning and value of
anonymity in the information age as ‘unreachability’.
A range of scholars offer many accounts of the meaning
and construction of identity, generally and in the con-
text of ambient intelligence and profiling.
Against this
backdrop the legal scholarly account of the meaning of
identification is inadequate.
This lack of academic consideration might be par-
tially explained by the fact that the Article 29 Working
Party, an EU advisory authority on data protection un-
der the former 1995 Data Protection Directive, defined
what an identified person means in its 2007 opinion on
the concept of personal data: ‘[i]n general terms, a natu-
ral person can be considered as “identified” when,
within a group of persons, he or she is “distinguished”
from all other members of the group’.
The same ex-
planation arguably holds for the concept of personal
data in the GDPR, since there are no fundamental dif-
ferences between the definitions of personal data under
Sector (BayLDA). The report of the Bavarian data protection authority is
not available online, but is referred to in Fraunhofer Institute for
Integrated Circuits IIS, (n 10).
15 This is according to Fraunhofer Institute for Integrated Circuits IIS
(n 10).
16 Eg Bridges case discussed further on in this article (R (on the application
of Edward Bridges) v The Chief Constable of South Wales Police and
Secretary of State for the Home Department [2019] EWHC 2341 (Admin)
at 122-125 and R (on the Application of Bridges) v South Wales Police
[2020] EWCA Civ 1058 at 46).
17 Eg Google’s FLoC alternative to the tracking-based targeted advertising
discussed further Chetna Bindra, ‘Google Ads. Building a Privacy-first
Future for Web Advertising’ (25 January 2021, <
ucts/ads-commerce/2021-01-privacy-sandbox/>) accessed 19 February
18 R Leenes, ‘Do They Know Me? Deconstructing Identifiability’ (2008)
4(1&2) University of Ottawa Law & Technology Journal 135, 141–42.
Although Leenes uses the word ‘identifability’, in effect he is talking
about identification.
19 Ibid.
20 Davis (n 8).
21 Catherine Jasserand, ‘Legal Nature of Biometric Data: From Generic
Personal Data to Sensitive Data’ (2016) 2 Eur Data Prot L Rev 297.
22 Gary T Marx, ‘What’s in a Name? Some Reflections on the Sociology of
Anonymity’ (1999) 15(2) The Information Society, 100.
23 Helen Nissenbaum, ‘The Meaning of Anonymity in an Information Age’
(1999) 15(2) The Information Society 141–44.
24 Eg contributions to Ian Kerr, Valerie Steeves and Carole Lucock (eds),
Lessons From the Identity Trail: Anonymity, Privacy and Identity in a
Networked Society (OUP, Oxford, New York 2009); Katja de Vries,
‘Identity, Profiling Algorithms and a World of Ambient Intelligence’
(2010) 12 Ethics and Information Technology 71–85.
25 WP136, 12.
Nadezhda Purtova From knowing by name to targeting 165
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the 1995 Directive and the Regulation. This approach
includes identification by name, but also other modes
of ‘zoom[ing] in on a flesh and bone individual’.
authority of the Working Party when it comes to the
data protection on the ground is undoubted, and its
opinion on the concept of personal data is the most
comprehensive and influential guideline for the control-
lers as to how this concept should be used in practice.
The general perception of the meaning of identification
under the GDPR following from the WP29 interpreta-
tion is thus that it is broad, flexible, and generously ac-
commodating to the realities and challenges of the
modern data processing practices.
Indeed, the mean-
ing of identification as distinguishing a person from a
group should bring the cases of targeted advertising,
profiling, and others where the name of a person is of
no consequence to the protective bosom of the GDPR.
Perhaps for this reason the data protection scholarship
seems to be comfortably content with the status quo in
law and literature.
However, the status quo has been resting on shaky
grounds. The position of the Working Party, and hence
the ‘distinguished from’ approach to identification, are
not formally binding. The Court of Justice of the
European Union (CJEU), the only body with authority
to issue binding interpretations of the GDPR, was long
silent on the meaning of identification. While the Court
did follow the Working Party in interpreting the ‘infor-
mation’ and ‘relating to’ elements of the concept of per-
sonal data in Nowak,
it also has a record of not
following the lines of interpretation chosen by the
WP29 earlier.
To complicate matters further, the
Court in its 2016 Breyer decision
appeared to have
invalidated the understanding of identification as distin-
guishing or being distinguished from a group, advanced
by the Working Party and granting the GDPR protec-
tion a broad reach. Without any detailed consideration
about the meaning of identification, the Court in Breyer
dismissed a dynamic IP (Internet Protocol) address as
an identifier sufficient to identify a person,
while one
of the core functions of an IP address is exactly to
distinguish one web visitor, or at least a location on the
network, from another.
This brief consideration seems to restrict the inter-
pretation of identification under the GDPR to the iden-
tification by name or a similar unique identifier
representing one’s civil identity, the narrowest meaning
of identification possible.
This effectively takes cook-
ies, IP addresses, and other online trackers,
and with
them a large part of online tracking and discrimination,
but also not name-tied individual profiling and (real-
time) automated decision-making, among others
enabled through some of the new technologies such as
facial detection, outside of the scope of the data protec-
tion law, and deprives people affected by these practices
of legal protection that the GDPR would have granted,
was the identification interpreted broadly. The very lim-
ited scholarly commentary on the Breyer case has largely
overlooked this remarkable and consequential departure
of the CJEU from the WP29 interpretation.
the question remains: how should identification under
the GDPR be understood?
This article will answer this question in two steps.
First, it will examine the meaning of identification out-
side of the legal context (the Section ‘Meaning and
Socio-Technical Approaches to Identification outside of
the GDPR’). It will offer an integrated typology of iden-
tification as a process and result of distinguishing a per-
son in a group. The typology builds on three prominent
socio-technical accounts of identification: four identifi-
ability types by Leenes, seven types of identity knowl-
edge by Marx, and anonymity as unreachability by
Nissenbaum. In addition to the established types, I will
identify targeting as a new identification type, where to
identify by way of targeting means to select a particular
individual from a group as an object of attention or
treatment in a single moment of time. The argument
will build, among others, on the literatures on calcu-
lated publics, profiling in recommender systems, price,
and content personalization. Second, I will focus on the
legal meaning of identification under the GDPR. I will
build a case that all five identification types not limited
26 Ibid 13–14.
27 See eg Lee A Bygrave and Luca Tosoni, ‘Article 4(1) Personal data’ in
Christopher Kuner and others (eds), The EU General Data Protection
Regulation (GDPR). A Commentary (OUP, Oxford 2020).
28 Peter Nowak v Data Protection Commissioner, Case C-434/16 [2017]
29 A recent example is a decision in Google Spain SL, Google Inc v Agencia
nola de Proteccio´n de Datos and Mario Costeja Gonza´ lez Case C-131/
12 [2014] ECLI:EU:C:2014:317 [31] et seq. where the Court found a
search engine provider a controller, contrary to the earlier position of the
Article 29 Working Party.
30 Patrick Breyer v Bundesrepublik Deutschland, Case C-582/14, [2016]
31 Breyer [38].
32 Davis (n 8) 17 et seq.
33 Ibid 17.
34 Except a limited number of cases when the data processed also contains
information revealing identity, eg vanity searches.
35 The author was able to locate very few papers published by the time of
writing that discuss Breyer and none of them, besides Davis, discuss the
Court’s stance on the meaning of ‘identified’ in any significant detail.
The papers reviewed include Frederic J Zuiderveen Borgesius, ‘Breyer
Case of the Court of Justice of the European Union: IP Addresses and the
Personal Data Definition’ (2017) 3(1) European Data Protection Law
Review 130; Alan Reid, ‘The European Court of Justice Case of Breyer’
(2017) 1 (2) Journal of Information Rights, Policy and Practice; Bygrave
and Tosoni (n 27).
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to civil identity identification are covered by the GDPR
meaning of identification. It is an easy conclusion to
draw if one follows a non-binding interpretation of
Article 29 Working Party that to identify means to dis-
tinguish one in a group. This approach will be detailed
in the section ‘The Article 29 Working Party
Interpretation of the GDPR’. In the section ‘Meaning of
Identification in CJEU’s case law’ I review the CJEU
case law with relevance to the meaning of identification,
including Breyer and its potentially restrictive impact. I
then propose a contextual interpretation of Breyer in
light of the facts of the case, which negates Breyer’s re-
strictive potential and brings all types of identification,
including non-civil identity ones, within the meaning of
identification under the GDPR. The section’
Conclusion: What This Means for Data Protection’ will
conclude with a discussion of the implications of this
broad reading of identification for EU data protection
law practice and research.
Meaning and socio-technical approaches
to identification outside of the GDPR
Non-legal, or ordinary meaning of concepts always pro-
vides a foundation of their use in law, sometimes ad-
justed to the legislative history and intent, objectives
and general system of the piece of legislation at hand. In
English, identification means ‘the action or process of
identifying someone or something or the fact of being
and to identify means ‘to establish or indi-
cate who or what (someone or something) is ...; recog-
nize or distinguish ... ,’
where ‘to distinguish’ refers
to recognition or treating of someone or something dif-
The verb ‘to individuate’ is a synonym of ‘to
distinguish from others’ and ‘to single out’.
to Davis, the linguistic equivalents chosen in at least 14
non-English official EU language versions of the GDPR
have a similar meaning.
Consequently, a person is
identified when it is established who he or she is, when
he or she is recognized from being known before or
from some characteristics, or when that person is recog-
nized as a distinct individual or treated differently.
However, in addition to the dictionary meaning, there
are various sociological and socio-technical analyses of
what identification is. Without aiming at
comprehensive cataloguing of these analyses, the re-
mainder of this section will consider three prominent
accounts of the meaning of identification: the four types
of identification by Leenes, the seven types of identity
knowledge by Marx, and the account of anonymity as
unreachability (and hence identification as reachability)
by Nissenbaum.
Operational definitions of identification:
Leenes and Marx
Leenes and Marx propose what can be considered oper-
ational definitions of identification, i.e. they list practi-
ces that—when present—indicate that identification is
taking place. Leenes relies on the conceptualization of
identification as the process or fact of being singled out
or ‘individualized within a set of subjects, the identifi-
ability set’
and distinguishes four types of identifica-
look-up (l-), recognition (r-), classification (c-),
and session (s-) identification.
1. The look-up (l-) identification is an identification of
a named individual by an identifier, such as a name,
telephone or passport number, and even an IP ad-
dress, when there is a registry, directory, or a table
that connects that identifier to a named individual
(ie his/her civil identity). Using an l-identifier, an in-
dividual can be ‘looked up’ in the real world, hence
the name.
2. Recognition (r-) identification refers to the identifica-
tion of an individual without a reference to his/her
civil identity and requires presence or activity of an
individual. An individual is identified from being
known before or by presenting certain features, ie
‘she presents an identifier, token or feature set (e.g.
description of physical appearance), known or rec-
ognizable as valid by the recipient, to the entity per-
forming the identification’.
For instance, a token
(eg a cloak room token) allows the recipient (a cloak
room clerk) to recognize the holder as someone, or
something, or as being entitled to something (eg to
receive a coat checked in in the cloak room).
Facial recognition is an example of r-identification.
An individual’s face is compared to a facial template
made during a preceding interaction with that indi-
vidual, to verify if that individual is, eg a repeated
visitor of a store, or has authorization to enter a
36 A Stevenson, J Pearsall and P Hanks (eds), Oxford Dictionary of English
(3rd edn, OUP, Oxford 2010) 868.
37 Ibid 869.
38 Ibid 509.
39 Ibid 891.
40 Davis ((n 8) 18) considered 15 out of the 23 non-English versions.
41 Leenes (n 18) 147–48.
42 Leenes calls them types of identifiability, but the types he proceeds to de-
scribe do not refer to the possibility of identification in future but rather
to the process of identification. Therefore I consider the typology he pro-
poses to be a typology of identification.
43 Leenes (n 18) 148.
44 Ibid 150.
45 Ibid.
Nadezhda Purtova From knowing by name to targeting 167
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building (if facial recognition is used as a method of
biometric authentication). Without the need to es-
tablish an individual’s civil identity, r-identifiers
connect several interactions with one individual to-
gether and ‘enable personalisation of experience’.
Persistent cookies, device-generated advertising IDs,
and IP addresses are examples of r-identifiers, and
ecommerce is one area where establishing one’s civil
identity is not necessary and r-identification is used
a lot,
among others for consumer profiling and
targeted advertising.
3. In case of the classification (c-) identification,individu-
ing] group of category’.
The purpose is not to
establish an individual’s civil identity or recognize
him or her, but to classify an individual as a member
of one or several groups. While categorization is often
achieved through observing individuals over time, eg
through (online) tracking and use of l- or r-identifiers,
it can also exist independently. In this case, a preexist-
ing knowledge of the categories and of the attributes
ries is required.
Facial detection technology allowing
to segment passers-by of smart ad boards into audi-
ence segments and demonstrate segment-tailored ads
would be an example of classification not relying on
tracking and l- or r-identification.
4. Session (s-) identification aims to track an individual
during a particular interaction, and the lifetime of
the s-identifiers is restricted to the duration of that
An example is session cookies that al-
low an online shop to individualize a visitor’s shop-
ping experience, eg make sure the website
remembers the items in a shopping basket.
Marx presents a sociological typology of identification
(the opposite of anonymity) that he understands as
‘identity knowledge’.
According to Marx, there are at
least seven types of identity knowledge, also reflecting
degrees of identifiability: (i) legal name, (ii) locatability,
(iii) pseudonyms that can be linked to legal name and/
or locatability, (iv) pseudonyms that cannot be linked
to other forms of identity knowledge, (v) pattern
knowledge, (vi) social categorization, and (vii) symbols
of eligibility/noneligibility.
1. Identification by a ‘legal name’ involves a full name
that is presumed unique in a given context (eg only
one child named John Smith is born to a particular
set of parents) and connects to the information ‘bio-
logical or social lineage’ and a large amount of other
information about a person.
2. Identification as ‘locatability’ involves ‘reachability’
of an individual by an address, actual or in the cy-
berspace (an IP address would be a good example of
reachability in the cyberspace). While it does not re-
quire knowledge of an individual’s civil identity or a
pseudonym, it does imply the ability to reach a per-
son and treat him or her in a certain way, eg block
or grant access, charge or penalize.
3. Identification by ‘pseudonyms that can be linked to
legal name and/or locatability’ involves ‘alphabetic
or numerical symbols’, ie pseudonyms, that link to
the person’s name or address. Such identification
usually involves a third trusted party which serves as
a buffer to facilitate a compromise between preserv-
ing one’s real identity or address but achieving some
degree of identification.
4. Identification by means of ‘pseudonyms that cannot
be linked to other forms of identity knowledge’
refers to the identification by symbols, names or
pseudonyms that, ‘under the normal circumstances’,
cannot be connected to a person, either due to spe-
cial anonymization measures or due to the fact that
the identifier is fraudulent, such as the pseydonyms
used by spies or con artists.
5. Identification by ‘pattern knowledge’ involves iden-
tification by reference to a repeated observation of
‘distinctive appearance or behavior patterns’
, not
connected to the name (civil identity) or the locat-
ability of a person. Examples that Marx cites are rec-
ognizing someone you repeatedly met on the metro
as someone you ‘know’, recognizing a donor by a re-
peated pattern of donation, a criminal by a pattern
of his crimes, etc.
6. Identification may happen by ‘social categorisation’
since ‘many sources of identity are social’.
individuals can be identified by gender, ethnicity,
organizational membership and other classifications
46 Ibid.
47 Ibid.
48 Ibid 151.
49 Ibid.
50 Ibid 152.
51 Marx (n 22) 100.
52 Ibid 100.
53 Ibid.
54 Ibid 101.
55 Ibid.
56 Ibid.
57 Ibid.
58 Ibid.
59 Ibid.
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which do not ‘differentiate the individual from
others sharing them’.
7. Identification by ‘symbols of eligibility/noneligibil-
ity’ involves ‘certification’ where the possession of
knowledge such as possession of a code word, arti-
facts, such as a ticket or a smart card, or a skill, eg
ability to swim, warrants a particular treatment, eg
entitlement for a reimbursement, or a sanction for
system abusers.
Nissenbaum’s anonymity as unreachability
While Helen Nissenbaum does not discuss the meaning
of identification directly, her work on the meaning and
value of anonymity is of immediate relevance for con-
ceptualization of identification. Identification and ano-
nymity are the opposites, and therefore the meanings of
these concepts are intimately related. In ‘The Meaning
of Anonymity in an Information Age’
Nissenbaum ar-
gued that the value of anonymity has traditionally been
to ensure unreachability, ie to ensure that when one acts
in a certain way, no one would knock on his door ‘de-
manding explanations, apologies, answerability, punish-
ment or payment’.
While the best way to ensure this
in the past was to remain nameless, ‘the power of infor-
mation technology to extract or infer identity from
non-identifying signs or information’ has changed this,
and remaining nameless or withholding other unique
persistent identifiers in place of a name such as a social
security or a passport number is no longer sufficient to
protect unreachability.
The current dangers of data
processing are not limited to eg one government body
connecting its record on someone to the record of that
person with another government body via, eg a social
security number.
As the advertising industry puts it,
‘[t]he beauty of what we do is we don’t know who you
are ... We don’t want to know anybody’s name. We
don’t want to know anything recognizable about them.
All we want to do is ... have these attributes associated
with them’.
This analysis suggests that, if anonymity
should be understood as unreachability, identification
should be understood as the process or the fact of some-
one being reached.
Synthesis: towards an integrated
operationalization of identification and
targeting as identification
The remainder of this section is a proposal for an inte-
grated socio-technical operationalization of identifica-
tion. The question to be answered is: which practices
constitute identification in concrete terms. The two ty-
pologies reviewed may already be considered operation-
alizing identification. This section will integrate and
refine them, also taking into account Nissenbaum’s per-
spective on identification as reaching a person, to reflect
the conceptual meaning of identification fully. The exer-
cise identifies a new type of identification not articu-
lated before, ie targeting.
Juxtaposing identification typologies
The three perspectives on identification reviewed above
agree with each other well, and reflect an understanding
of identification in line with its dictionary meaning, as a
process or fact of recognizing or distinguishing some-
one. The typology by Leenes is better suited to be a
foundation of an integrated understanding of identifica-
tion compared to that by Marx. The typology offered by
Marx is less suitable as a typology of ‘identification’, be-
cause, as Marx states, it reflects not only the meaning
but the degrees of identifiability as a ‘possibility of’
identification rather than purely of identification as a
fact or a process. As a result, it is not entirely clear
where Marx draws a line between identification and
identifiability, eg if he considers identification by name
as the only mode of true identification (type 1) while
the remaining types are meant to refer to degrees of
identifiability. Leenes’ typology is more clear-cut, i.e. fo-
cuses on the essential features of each type without
overlap, but also provides a nuance that Marx’s typol-
ogy does not have. To name one example, Marx does
not account for the lifespan of identifiers as Leenes
All the types identified by Marx fit under one
and some under two of the types distinguished by
Leenes (as presented in Table 1).
Three out of seven types of identification distin-
guished by Marx match Leenes’ identification types:
Marx’s identification by a legal name (type 1) fits within
Leenes’ look-up identification, identification by pattern
60 Ibid.
61 Ibid.
62 Nissenbaum (n 23) 141–44.
63 Ibid 142. See also Daniel Solove, Understanding Privacy (Harvard
University Press, Harvard 2008) 125 where Solove expresses a similar
view on identification, namely, that identification links the digital person
created by aggregation of data points to a person in real space.
64 Nissenbaum (n 23) 142.
65 Solon Barocas and Helen Nissenbaum, ‘Big Data’s End Run around
Anonymity and Consent’ in Julia Lane and others (eds), Privacy, Big Data,
and the Public Good. Frameworks for Engagement (CUP, New York 2019)
66 Cindy Waxer, ‘Big Data Blues: The Dangers of Data Mining’ 4 November
2013 Computerworld, <
9243719/Big_data_blues_The_dangers_of_data_mining>cited in
Barocas and Nissenbaum (n 65) 54.
67 As evident in case of session identification.
Nadezhda Purtova From knowing by name to targeting 169
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knowledge (type 5) fits under recognition identification;
social categorization (type 6) is equivalent to Leenes’
classification identification. Yet, four out of seven types
display characteristics of two identification types
according to Leenes: identification by a pseudonym that
can be linked to civil identity (type 3) and locatability
(type 2) fit both under the look-up and recognition
identification. The former is the case because Marx pre-
sumes a pseudonym to be connected to a person’s civil
identity and only separated from that identity by a third
trusted party. This renders that person identifiable in
the look-up sense of identification. Similarly, a physical
or cyber (eg IP) address may serve as a look-up identi-
fier when connected to a person’s real world identity via
a registry, like it is the case with static IP addresses. At
the same time, both the pseudonym and locatability
identifiers can serve as recognition identifiers, eg to rec-
ognize and track interaction with individuals over time,
where, albeit possible, the establishment of who a per-
son in the real world is not necessary, eg for the targeted
advertisement purposes. Marx’s identification by sym-
bols of eligibility (type 7) fits both under recognition-
and classification identification. If the distinctive feature
of this mode of identification is the resulting eligibility
for a particular treatment, it can be achieved both by us-
ing r- and c-identifiers: r-identifiers when certain treat-
ment is triggered by a token or another identifier
tagging a person as ‘known’ or ‘eligible’, eg to enter a
building based on facial recognition, and c-identifiers
when the treatment is triggered by a person displaying
characteristics of a group: male or female, reader of de-
tective novels, at high risk of diabetes, etc. Identification
by pseudonyms not linkable to civil identity or locat-
ability (type 4) fits both under recognition- and session-
identification, depending on the lifetime of the
Targeting—new identification type
Considering the two typologies together and in light of
Nissenbaum’s work reveals another mode of identifica-
tion that neither Leenes nor Marx articulate as a distinct
type. Yet, this identification mode is implied in the un-
derstanding of identification as individuation and dis-
tinguishing one from a group, including reaching a
particular person, and has sufficient defining features to
be distinguished as a separate identification type. This is
targeting (or t-identification).
To identify by way of targeting means to select a par-
ticular individual from a group as an object of attention
or treatment in a single moment of time. T-identification
is the most basic mode of individuation. It does not aim
at establishing civil identity. Unlike recognition- and to
Table 1. Relationship between Leenes’ and Marx’s typologies
Establishing civil identity via a
register that links an identifier
(name, passport number, etc.) to
a person in the real world
Recognizing a person as ‘known’
or eligible by ‘an identifier, a
token or a feature set’ seen as valid.
Classification of a
person as a
member of a
group or category.
Tracking of a user
during one
interaction, where the
of an identifier is
limited to a session.
Marx 1. Identification
by a legal name;
3. Pseudonyms that
can be
linked to legal
name and / or
2. Locatability;
4. Pseudonyms that
cannot be linked
to a legal name
or locatability;
5. Pattern
7. Identification by
symbols of
6. Social
4. Pseudonyms that
cannot be linked to a
legal name or
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some degree session identification, t-identification does
not rely on a persistent identifier such as an IP address or
cookies and does not aim to recognize an individual dur-
ing a future encounter. Instead, targeting occurs in real
time and at the single moment of contact. Unlike classifi-
cation identification, targeting does not aim to identify
an individual as a member of one or several groups and
does not require a pre-existing knowledge of the catego-
ries and of the attributes that put an individual in these
categories. Instead, the purpose of targeting is pure indi-
viduation, zooming in on a particular individual who is
distinct from others. This can be done in order to subject
that individual to tailored treatment or content.
Targeting can be achieved either by means of a unique
identifier that does not need to be persistent, or can be
based on the rich dataset, eg provided by a device in real
time and allowing unique characterization of an individ-
ual that distinguishes that individual from others.
An example of t-identification by means of a unique
identifier is identification by a media access control
(MAC) address. A MAC address is a unique identifier
usually assigned to a device by its manufacturer as a
hardware address for communication in a network. A
persistent MAC address enables continuous monitoring
of movements of a particular mobile device which
would amount to session identification, or recognition
of the same device on a repeated encounter which con-
stitutes recognition identification. As a countermeasure
against such tracking, many device manufacturers intro-
duced randomization of MAC addresses while devices
are scanning for networks. However, even when ran-
domized MAC addresses do not allow for tracking devi-
ces across time, each random MAC address—although
short-lived—is still unique and distinguishes one
unique device from another for the purposes of com-
munication in a network. T-identification is the use of a
MAC address, whether persistent or randomized, solely
in order to distinguish one device (and its user) from
another ‘in a single moment of time’ rather than facili-
tate tracking or recognition.
A human face is another unique identifier that can be
used for recognition of individuals (in the sense of r-
identification) when their facial data is matched to pre-
existing facial templates of known individuals.
However, facial data does not always have to be
matched to facial templates and does not have to lead to
recognition. In t-identification, facial data is used to dis-
tinguish one unique face from another in a single mo-
ment of time which is not aimed at recognition or
tracking. This can be done in the context of crowd
management, or in order to infer demographic and
emotional data from facial features and display advertis-
ing tailored accordingly.
An individual can be t-identified on the basis of a
unique characterization on the basis of a rich dataset.
When discussing identification by pattern knowledge,
Marx writes:
Some information is always evident in face-to-face interac-
tion, because we are all ambulatory autobiographies contin-
uously and unavoidably emitting data for others’ senses
and machines. ... This has been greatly expanded by new
With t-identification based on a rich dataset, the unique
identifier is not unique facial features or a MAC address,
but that unique data-driven ‘autobiography’ that a
user’s machine is broadcasting in real time and that
uniquely distinguishes that machine and its users from
others. The difference with the t-identification based on
a single identifier is that—in addition to purely distin-
guishing an individual—the rich dataset also provides
his or her description, a unique characterization.
Browser fingerprinting is one instance of such
information-emitting autobiography. Browser (or
web-) fingerprinting is a method used to collect de-
tailed information about the machine of a website visi-
tor, including a browser type and version, operating
system, language and security settings, screen resolu-
tion, and other parameters. These data form a ‘finger-
print’ that can be used to recognize browser users
when they are encountered again. But recognition is
not the only use of browser fingerprinting. The data
captured in the ‘fingerprint’ can be sufficiently rich to
enable a unique characterization of a person, to distin-
guish a person without a reference to earlier encoun-
ters. This would constitute identification in the sense
of targeting.
Sparse or dense matrices and embedding are exam-
ples of techniques that can be used here. To be t-identi-
fied on the basis of a rich dataset, one is characterized
or mapped in relation to a multiplicity of dimensions or
axes within a multidimensional space, where an axe can
be attributes, such as facial and physical dimensions,
interests, behaviour, or the attributes of the surrounding
context, eg a device, as a container for such behaviour.
Seaver suggests that the spread of sensory technology is
‘expected to provide even more contextual signals’, such
as the ambient noise level, acceleration, etc.
T-identification based on rich datasets shares some
similarities with classification identification in the sense
68 Marx (n 22) 101. 69 Nick Seaver, ‘The Nice Thing about Context is That Everyone Has It’
(2015) 37 (7) Media, Culture & Society 1102.
Nadezhda Purtova From knowing by name to targeting 171
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that the unique characterization is done based on static
or dynamic characteristics or attributes that could belong
to categories or groups. The difference is that, unlike
with classification which is essentially a result of putting
people in one or several boxes populated by many
(Russian, Dutch, 25-year-olds, blond or dark haired), in
case of t-identification, using the vocabulary of differen-
tial privacy, k¼1.
In other words, the more axes or
parameters of characterization are used, the fewer people
share the same location on the axes. The more parame-
ters are included, the closer the characterization is
approaching unique. Moor and Lury call this ‘personality
construction’ which is based on fragments of a personal-
ity of an individual relevant to some actors in some con-
what Delueze called dividuals.
Unlike with
classification and categorization, targeting is not con-
cerned with a person as a member of one or several
groups, but aims at personalization. An individual is
characterized by an overlap of a very large number of
attributes and classifications, where any group attributes
and classifications are increasingly not along the static
and socially constructed socio-demographic lines, but are
algorithmically constructed. The resulting overlap is rela-
tively unique.
T-identification on the basis of rich datasets is to a
large degree a product of a shift of classification practi-
ces towards algorithmic classification. As a result, the
categories in which people can be classified become less
stable and obvious and less transparent to a person be-
ing categorized or even to those doing the categoriza-
tion. While categorization based on widely used and
known and relatively static parameters such as age, so-
cial status, or ethnic origin and other socio-
demographic criteria is more obvious and transparent,
categorizations are increasingly done in the form of the
so-called ‘calculated publics”’
where the categories
and attributes are not socially but algorithmically con-
structed. As a result, the categories are dynamic, interac-
tive, iterative, descriptive but increasingly more
and so less obvious and transparent.
At present, identification by persistent identifiers in
the sense of l-identification, recognition or session
identification is certainly more common and more
known. Yet, t-identification might quickly become more
prevalent as a result of an interplay of a number of devel-
opments. The first such development is a push towards
more personalized content,
advertising and pricing.
Second, t-identification, especially based on rich datasets,
will likely become more widespread as a part of a larger
move towards context-aware computing,
According to
Seaver, ‘we are in for a future where data mining con-
cerns itself increasingly with the determination of con-
text, drawing on a range of signals to personalize more
precisely than the unified “person”’.
Finally, the popu-
lar perception of data processing risks is connected to
names and other persistent identifiers, and the focus of
the ‘privacy-preserving technologies’ and enforcement
efforts also lies on persistent look-up and recognition
identifiers. Targeting identification enables to reach a
unique individual with tailored content or treatment
without relying on those identifiers tainted by public and
enforcement attention, and therefore may well become
the winning strategy growing in popularity.
Temporal dimension of identification
Looking at the resulting types of identification from the
perspective of Nissenbaum’s work, it becomes clear that
the various identification types can also be characterized
based on a temporal dimension. Only the look-up and
recognition identification types involve a (somewhat)
persistent identifier that allows distinguishing, or reach-
ing, a particular person through time. Indeed, only
look-up and recognition identification, eg by name, ad-
dress, a static IP address, a token or a repeating pattern
of behaviour enable longitudinal observation, holding a
person accountable for his or her past actions, sanction-
ing, holding eligible or rewarding a person based on
something that took place in the more or less remote
past. Session identification also has this temporal fea-
ture, albeit limited to the lifetime of one interaction, eg
a website ‘remembers’ which item the visitor put in the
basket. Classification and targeting identification clearly
do not have such a longitudinal element. There an iden-
tified person is ‘reached’ or distinguished based on the
70 krefers to the number of people fitting into a group or category.
71 Liz Moor and Celia Lury, ‘Price and the Person: Markets,
Discrimination, and Personhood’ (2018) 11(6) Journal of Cultural
Economy 501–13.
72 Gilles Deleuze, ‘Postscript on the Societies of Control’ (1992) 59 October
73 Tarleton Gillespie, ‘The relevance of algorithms’ in Tarleton Gilespie,
Pablo Boczkowski and Kirsten Foot (eds), Media Technologies: Essays on
Communication, Materiality, and Society (Cambridge, MA: MIT Press)
177. See also Moor and Lury (n 71).
74 Eg as Seaver observes, ‘[i]n demographic marketing, groups of people
and groups of products are mutually defining: brand strategists
understand pizzas in terms of people and people in terms of pizzas’.
(Nick Seaver, ‘Algorithmic Recommendations and Synaptic Functions’
(2012) 2 Limn <
and-synaptic-functions/>accessed 19 February 2021).
75 Nick Couldry and Joseph Turow, ‘Advertising, Big data, and the
Clearance of the Public Realm: Marketers’ New Approaches to the
Content Subsidy’ (2014) 8 International Journal of Communication
76 As illustrated in Moor and Lury (n 71).
77 Seaver (n 69) 1101–09.
78 Ibid 1103.
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features he or she presents in real time, with real time
consequences. What results is an integrated typology of
identification as presented in Table 2.
The Article 29 Working Party
interpretation of the GDPR
Broad meaning of identification
The GDPR does not directly define identification. The
only relevant provision of the GDPR is the Article 4(1)
definition of personal data.
‘Personal data is any information relating to an identified
or identifiable natural person (‘data subject’); an identifi-
able natural person is one who can be identified, directly or
indirectly, in particular by reference to an identifier such as
a name, an identification number, location data, an online
identifier or to one or more factors specific to the physical,
physiological, genetic, mental, economic, cultural or social
identity of that natural person.’
The definition refers to an ‘identified and identifiable
natural person’, explaining that ‘an identifiable natural
person is one who can be identified’. Recital 30
non-name identifiers such as RFID that can enable
identification, but is inconclusive as to whether or not
an individual is ‘identified’ by a non-name identifier or
only ‘identifiable’. Recital 26 provides some guidance
on when a natural person should be considered identifi-
able and establishes the test of ‘the means reasonably
likely to be used ... to identify’, calling for all objective
factors of the case to be considered. Yet, while ‘identifi-
able’ in the definition clearly refers to the possibility of
identification, ie of being identified, no explanation of
what ‘identified’ means is given.
Some explanation is provided by the Article 29
Working Party. The Article 29 Working Party, an EU ad-
visory authority on the matters of data protection under
the 1995 Data Protection Directive (the DPD), adopted a
non-binding opinion on the concept of personal data
The current status of the opinion is not cer-
tain. On the one hand, it concerns the concept of personal
data in the old DPD and not the GDPR, the Article 29
Working Party itself no longer exists and is substituted by
a new advisory authority—the European Data Protection
Board (EDPB). Shortly after coming to existence, this
functional equivalent of the Article 29 Working Party en-
dorsed a number of Article 29 Working Party opinions,
On the other hand, an
argument can be made that the opinion retained its sig-
nificance also under the GDPR, since the concept of per-
sonal data has not undergone significant changes.
While in future the EDPB may choose to issue its own
Table 2. Integrated typology of identification
Establishing civil
identity via a
register that links
an identifier
(name, passport
number, etc.) to a
person in the real
Recognizing a person
as ‘known’ or
eligible by ‘an
identifier, a token
or a feature set’ seen
as valid.
Tracking of a user
during one
interaction, where
the lifetime of an
identifier is limited
to a session.
Classification of a
person as a member
of a pre-existing
group or category.
Selecting a
individual from a
group as an object
of attention or
treatment in a
single moment of
Temporal dimension
Persistent identifiers allow longitudinal
Limited persistent
tracking limited to
duration of one
No persistent identifiers
No longitudinal tracking
79 Recital 30 GDPR reads: ‘Natural persons may be associated with online
identifiers provided by their devices, applications, tools and protocols,
such as internet protocol addresses, cookie identifiers or other identifiers
such as radio frequency identification tags. This may leave traces which,
in particular when combined with unique identifiers and other informa-
tion received by the servers, may be used to create profiles of the natural
persons and identify them.’
80 WP 136 (n 3).
81 See <
wp29-guidelines_en>accessed 13 June 2022.
82 See eg Case C-434/16 Peter Nowak v Data Protection Commissioner
[2017] ECLI:EU:C:2017:994, Opinion of Advocate General Kokott [3].
Nadezhda Purtova From knowing by name to targeting 173
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GDPR-specific guidelines on the concept of personal data
and take a different view on what identification means, it
has not done so yet and its work programme for 2021–22
has given priority to other key data protection concepts
such as legitimate interest.
For this reason, the Article
29 Working Party opinion remains influential and will be
considered as such here.
WP29 adopts an understanding of identification
which is in line with its dictionary meaning: ‘[i]n gen-
eral terms, a natural person can be considered as
“identified” when, within a group of persons, he or she
is “distinguished” from all other members of the group’,
and ‘the natural person is “identifiable” when, although
the person has not been identified yet, it is possible to
do it’.
Throughout the text of the opinion the WP29
also uses other formulations as stand-ins for ‘to distin-
guish from the group’: to ‘single out a particular person’
or to ‘zoom in on a flesh and bone individual’.
The WP29 explains that identification is achieved
through the so-called identifiers. The identifiers are
‘particular pieces of information ... which hold a par-
ticularly privileged and close relationship with the par-
ticular individual’,
like a name, ‘outward signs of the
appearance of this person, like height, hair colour,
clothing, etc... or a quality of the person which cannot
be immediately perceived, like a profession, a func-
The WP29 does not shed any light on the crite-
ria that determine that close or privileged relationship.
Intuitively, not all of the examples of identifiers hold
that special and privileged position in relation to an in-
dividual. While a name, a social security number, and
perhaps some appearance traits, eg a face, can be said to
be in that particular relationship to an individual due to
a psychological bond (eg with a name and a face) or be-
cause they are unique to that individual (eg a face and a
social security number), it is difficult to call a relation-
ship between an individual and his or her hair colour,
height or profession ‘privileged’ or particularly close,
since hundreds of thousands of people may share these
characteristics, and individual can change at least some
of those characteristics (eg by dying the hair, wearing
hilled shoes or changing a career). Which aspect of the
relationship between a piece of information and an in-
dividual makes it special, making that piece of
information an identifier according to the WP29,
remains guesswork. Therefore a simpler and more con-
sistent way to define an identifier would be as a piece of
information that, alone or in combination with other
identifiers, distinguishes a person in a group.
What requires more attention though is what the
WP29 understands as ‘direct’ and ‘indirect’ identifica-
tion, and consequently when an individual is identified
(or identifiable) ‘directly’ and ‘indirectly’. The WP29
explains that a person may be identified or identifiable
either directly or indirectly.
In other words, ‘directly
or indirectly’ in the definition of personal data (‘an
identifiable natural person is one who can be identified,
directly or indirectly’) applies to an identified as well as
identifiable natural person, and not just to the latter.
This follows from the legislative history of the definition
of personal data in the 1995 Directive where the com-
mentaries to the amended Commission proposal also
distinguish two ways in which a person may be identi-
fied: ‘[A] person may be identified directly by name or
Some confusion may occur where the commentary
the WP29 cites explains that
‘a person may be identified directly by name or indirectly
by a telephone number, a car registration number, a social
security number, a passport number or by a combination
of significant criteria which allows him to be recognized by
narrowing down the group to which he belongs (age, occu-
pation, place of residence, etc.).’
The commentary suggests that only identification by
name should be considered as direct identification, and
identification by other single identifiers such as a tele-
phone number, a car registration number, a social secu-
rity number, or a passport number should be considered
indirect, just as the identification by a combination of
significant criteria that narrow down the group to which
a person belongs should be considered as a case of indi-
rect identification. While the WP29 does not explicitly
disagree with this understanding, its further explanation
testifies to this effect. While the opinion is quite detailed,
it is not always conclusive for the purposes of our analy-
sis, specifically, because the explanation is structured
along the lines of ‘directly’ versus ‘indirectly’ identified or
83 European Data Protection Board, ‘EDPB Work Programme 2021/2022’
(available online at <
strategy-work-programme_en>, accessed 30 may 2022).
84 WP136 12. The ‘distinguished from the group’ understanding of identifi-
cation seems to have been broadly adopted in Europe. The European
Agency for Fundamental Rights and the Council of Europe explain that
identification ‘requires elements which describe a person in such a way
that he or she is distinguishable from all other persons and recognizable
as an individual’. Handbook on European data protection law (European
Agency for Fundamental Rights and Council of Europe, 2018) <https://>
85 WP136 13–14.
86 Ibid 12.
87 Ibid 12.
88 Ibid 12.
89 Ibid 12–13.
90 Ibid.
174 ARTICLE International Data Privacy Law, 2022, Vol. 12, No. 3
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identifiable, rather than ‘identified’ and ‘identifiable’. The
result is that it is not always possible to separate the
WP29 considerations that concern ‘identified from the
considerations concerning ‘identifiable’. For this reason,
this analysis is bound to be an interpretation of the
WP29 opinion, rather than its restatement.
Regarding ‘directly’ identified or identifiable persons,
the WP29 observes that the name ‘is indeed the most
common identifier, and, in practice, the notion of ‘iden-
tified person’ implies most often a reference to the per-
son’s name’.
Yet, ‘a name may itself not be necessary
in all cases to identify an individual’.
Other ‘unique
identifiers’ can be used to distinguish one person from
another, such as identifiers assigned to persons in com-
puter files (eg file numbers), or web traffic surveillance
presumably, such as cookies, IP addresses, and
other online identifiers. Since a computer is the individ-
ual’s contact point, the ability to identify an individual
‘no longer ... requires the disclosure of his or her iden-
tity in the narrow sense’, and does not ‘necessarily mean
the ability to find out his or her name’.
Perhaps, fol-
lowing the same logic, the final definition of personal
data in the 1995 Directive which transitioned into the
GDPR without significant changes does not follow the
Commission verbatim and lists the name among other
identifiers which can identify both directly and indi-
rectly, depending on the context.
In sum, a person can
be directly identified not only by name but by reference
to another ‘unique identifier’.
Consequently, ‘indirect’ identification refers to the
identification through ‘unique combinations’ of non-
unique identifiers. This is what the definition of per-
sonal data in part on the modes of identification refers
An individual can be identified indirectly
... by reference to ... one or more factors specific to the
physical, physiological, genetic, mental, economic, cultural
or social identity of that natural person.’
A person is indirectly ‘identified’ when the unique com-
bination of non-unique identifiers is complete and ena-
bles to distinguish that person from a group, while
when additional information is necessary, that person is
indirectly ‘identifiable’.
Importantly, whether or not an individual is identi-
fied by the available identifiers heavily depends on the
Similar to how all objective factors need to be
considered while assessing whether or not an individual
is identifiable,
‘the question of whether the individual
to whom the information relates is identified or not
depends on the circumstances of the case’.
For in-
stance, even a name may be insufficient to identify a
particular person within a population of a country,
when it is a common name, but will likely identify a pu-
pil in a classroom.
In the former case, additional in-
formation, such as address and date of birth, might be
necessary for what will be ‘indirect identification’. At
the same time, an otherwise non-unique identifier, such
as that a person is wearing a black suit, may become
unique and hence be sufficient to directly identify a per-
son in a particular context, eg to distinguish one person
from the people standing at a traffic light without any
additional information.
This results in the meaning of identification as pre-
sented in Table 3. A person is ‘identified directly’, ie dis-
tinguished from the group, by name or another unique
identifier which is obtained and where no additional in-
formation is necessary. A person is directly ‘identifiable’
when such a unique identifier is not obtained yet, but it
is reasonably likely to be obtained. A person is ‘identi-
fied indirectly’ by a unique combination of non-unique
identifies which is complete, ie no additional informa-
tion is needed to identify. A person is ‘indirectly identi-
fiable’ when such unique combination of identifiers is
incomplete and additional information is necessary to
be able to distinguish that person.
To illustrate, a website visitor would be ‘directly
identified’ to the website provider by the IP address
during the browsing session, because the IP address,
whether static or dynamic, is the only and in this case
unique identifier that allows the website provider to dis-
tinguish one visitor from another. For an example of
what would constitute ‘directly identifiable’, suppose a
municipal government, acting within its legal compe-
tence, orders all inhabitants of the city of The Hague to
stay inside after 20:00. The information that all inhabi-
tants of the city are likely to be inside is information
91 Ibid 13.
92 Ibid 14.
93 Ibid 14.
94 Ibid. This point was also made by eg Borgesius (n 5), but in relation to
the meaning of ‘identifiable’.
95 I refer to this particular wording of Art 4(1) GDPR here: an individual
can be identified ‘directly or indirectly, in particular by reference to an
identifier such as a name, an identification number, location data, an on-
line identifier or to one or more factors specific to the physical, physio-
logical, genetic, mental, economic, cultural or social identity of that
natural person’.
96 WP136 13.
97 ‘[T]he extent to which certain identifiers are sufficient to achieve identifi-
cation is something dependent on the context of the particular situation’
98 Recital 26 GDPR.
99 WP136 13.
100 Ibid.
101 Ibid 13.
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that relates to the natural persons who are ‘directly
identifiable’. While the names of the inhabitants may
not be directly available, they are easy to obtain eg from
a phone book or a city registry. While this article is
reviewed anonymously, a combination of several group
characteristics such as current institutional affiliation,
gender, nationality, age and field of expertise would be
sufficient to specifically pinpoint its author who as a re-
sult would be ‘identified indirectly’. Suppose one of
these characterizations would be missing, making it
prima facie impossible to single out one specific person
in a group, but it was reasonably likely to obtain this ad-
ditional information. In this case the author would be
‘indirectly identifiable’.
Objectively and relatively unique identification
While not discussed in detail by the Working Party, the
issue of uniqueness of identification is salient for the
meaning of identification under the GDPR.
Identification can be either objectively unique, where
the chance that another person would have the same
identifying attribute(s) is or approaches zero, or it can
be relatively unique, where an identifying attribute may
not be unique in the world, but is unique in a group or
a sample. The threshold the Working Party seems to
have adopted is of the relative identification. This fol-
lows from the emphasis the Working Party puts on the
significance of context for identification. To restate
WP136, ‘the extent to which certain identifiers are suffi-
cient to achieve identification is something dependent
on the context of the particular situation’.
A man
wearing a black suit by a traffic light is identified by an
otherwise not unique attribute (wearing a black suit) in
a specific context, ie among a group of passers-by near a
traffic light. Another relevant example the WP136
brings, albeit in the context of identifiability, is of key-
coded data in research. If codes used to identify research
participants are not unique, and the same code (eg 123)
is used to distinguish individual participants in different
towns and for different years, a possibility of combining
the non-unique code with the town and the year will
render a participant identifiable
and identified if the
combination of the code, town and year is complete
and held by one actor. That is, according to WP136, an
individual will be identified in the sense of the GDPR
both by an objectively unique identifier (or a combina-
tion of identifiers), and by an identifier that is unique in
a particular context, within a sample, or in a group.
Should it be impossible, for technical, logistical, orga-
nizational or other reasons, to establish with certainty
that information relates to only one unique individual in
a given context, the Working Party suggests that the in-
formation is still to be regarded as personal data but relat-
ing to an ‘identifiable’ rather than identified natural
person. That is, provided the purpose of processing is to
identify individuals in a dataset,
or the controller can-
not establish with absolute certainty that the individuals
to whom the data relates cannot be identified.
All five types of identification within the scope
of the GDPR
The WP29 approach to identification ensures a far reach
of the GDPR as it encompasses the entire integrated ty-
pology of identification proposed here, albeit with some
reservations. Look-up, recognition, session, and target-
ing identification do certainly fall within the meaning of
identification as distinguishing from the group, as they
allow to zoom in on someone as an individual distinct
from others, even if the individual remains nameless, or
the zooming in is not continuous in time and is limited
to duration of a contact or browsing session like in case
of targeting and session identification.
Table 3. Meaning of ‘directly or indirectly identified or identifiable’
IDENTIFIED Distinguished by name or another
unique identifier, which is obtained.
Distinguished by a unique combination of
non-unique identifiers which is complete
(ie no additional information is necessary)
IDENTIFIABLE The unique identifier is not yet
available, but is reasonably likely to
be obtained.
By a unique combination of non-unique
identifiers where the combination is incomplete
and additional information is necessary and is
reasonably likely to be obtained.
102 Ibid.
103 Ibid 19.
104 Ibid 16, 19, see also the video surveillance example.
105 Ibid 17 (the IP addresses example: the controller ‘is not in a position to
distinguish with absolute certainty that the data correspond to users that
cannot be identified’).
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To illustrate, tracking someone by the IP address con-
stitutes processing of personal data of an identified person,
either in the sense of recognition identification if the indi-
vidual is recognized by his static IP address on a repeated
encounter, or in the sense of session identification if the IP
address—static or dynamic—is used to distinguish one
node in a network from others for the duration of a ses-
sion. The ability to establish civil identity of the user is ir-
relevant, and assessing identifiability is not necessary.
Using a rich dataset to target tailored content at an indi-
vidual website visitor is processing of personal data relat-
ing to an identified natural person in the sense of targeting
identification when the dataset is in use. This is because
displaying tailored content different from what others vis-
iting the website see constitutes reaching or distinguishing
a person in a group visiting the website at that time. The
same dataset when not in use relates to an identifiable per-
son given its purpose to distinguish, ie to identify.
Similarly, using rich datasets—stored locally on a user’s
device or otherwise—to uniquely characterize individuals
first in order to put them in larger categories constitutes
targeting identification and hence processing of data relat-
ing to identified individuals even when these individuals
are treated the same, ie as groups, later. This seems to be
Cohorts, or FLoC, alternative to the third-party cookie
tracking in interest-based advertising. While the idea is to
‘hide individuals “in the crowd”’ and ‘use on-device proc-
essing to keep a person’s web history private on the
to form cohorts sharing the same interests,
similar to the word embedding in the natural language
processing, the technique still needs to use the rich brows-
ing history data to map each individual in a multidimen-
sional space to see how they connect to each other.
The status of classification as identification under the
GDPR is more complex. Classification on its own is not
identification in the sense of the GDPR, even when a
broad WP29 approach to identification is adopted. As
WP29 has itself pointed out in the context of facial
‘[a facial] template or set of distinctive features used only in
a categorisation system would not, in general, contain suffi-
cient information to identify an individual. It should only
contain sufficient information to perform the categorisa-
tion (e.g. male or female). In this case it would not be per-
sonal data provided the template (or the result) is not
associated with an individual’s record, profile or the origi-
nal image (which will still be considered personal data).’
In other words, categorization for as long as it does not
uniquely distinguish an individual from a group but sim-
ply assigns an individual to a group, does not prima facie
constitute identification, unlessitisappliedtoanindivid-
tification. This is similar to the discussion about the status
of group profiles as personal data. As among others Koops
observes, a group profile becomes personal data when ap-
plied to an identified or identifiable person.
However, and importantly, because the WP29
instructs that the possibility to identify heavily depends
on a context, classification of a person can become iden-
tification in its own right and without the necessary
connection to other modes of identification under cer-
tain circumstances which make the otherwise non-
unique classification a unique identifier. Think of a clas-
sification of an individual as a redhead. Although rare,
there are still thousands of people with the red hair col-
our, so classifying someone as a redhead will not be suf-
ficient to distinguish one person from the population of
a country, but might be enough in a classroom.
Similarly, recall the Working Party example of a person
wearing a black suit: an identifier otherwise not unique,
but sufficient to distinguish one particular person
among the passers-by at the traffic light.
Meaning of identification in CJEU’s case
From Lindqvist to Breyer: from inconclusive to
restrictive interpretation of identification?
Has the CJEU been similarly generous in applying the
concept of identification? The Court of Justice ruled on
the meaning of personal data in its very first data pro-
tection case, Lindqvist,
and on a number of occasions
since then. However, compared to the WP29 opinion, it
has not been nearly as articulate on the meaning of the
various elements of this concept, including identifica-
tion. The Court often generally states that the scope of
the 1995 Directive—in force when most of the data pro-
tection case law was formed—is very wide and the per-
sonal data covered by the Directive are varied.
bulk of the relevant cases simply state that a particular
type of data is personal, without much explanation or
106 Google’s FLoC alternative to the tracking-based targeted advertising in
Bindra (n 17).
107 Article 29 Working Party ‘Opinion 02/2012 on facial recognition in on-
line and mobile services’ (WP192, adopted on 22 March 2012) 4.
108 Bert Jaap Koops, ‘Some Reflections on Profiling, Power Shifts, and
Protection Paradigms’ in Mireille Hildebrandt and Serge Gutwirth (eds),
Profiling the European Citizen: Cross-disciplinary Perspectives (Springer,
Dordrecht 2008) 331; Borgesius (n 5) 260.
109 Bodil Lindqvist Case C-101/01 [2003] ECR I-12992, ECLI:EU:C:2003:596.
110 O
¨sterreichischer Rundfunk and Others, Joined Cases C-465/00, C-138/01
and C-139/01 [2003] ECR I-4989, ECLI:EU:C:2003:294
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discussion. Among others, the name of a person but
also his telephone coordinates or information about
working conditions or hobbies,
his address,
work periods, rest periods and corresponding breaks
and intervals,
monies paid by certain bodies and the
amounts of earned or unearned incomes
and assets of natural persons
have been explicitly
pronounced to be personal data. Interestingly, Lindqvist
touches upon the meaning of identification in two para-
graphs but is inconclusive, first, on whether or not the
data involved is personal because it relates to persons
who are identified or identifiable,
and whether or not
identification in the sense of data protection law can be
done via non-name identifiers alone, or in conjunction
with a name.
Only relatively recently, did the Court include a
more detailed analysis of what particular elements of
the concept ‘personal data’ mean.
The case law on
the meaning of identification is very limited and incon-
clusive. In Scarlet v SABAM, the Court ruled that the IP
addresses of internet users were protected personal data
because they ‘allow users to be precisely identified’,
which can be interpreted to mean both that the com-
puter users behind the IP addresses are ‘identified’ and
the IP addresses are the identifiers, and that the com-
puter users are ‘identifiable’ because the IP addresses
make the identification reasonably likely.
In the Breyer case the Court focused specifically on the
meaning of ‘identifiable’. The judgement was welcomed
as the assent of the Court to the absolute approach to
identifiability in EU data protection law, first declared in
Recital 26 of the Data Protection Directive and then ad-
hered to by the WP29.
Supporting a broad interpreta-
tion of the criterion of identifiability and hence a broad
meaning of the concept of personal data, Breyer has gen-
erally been a positive development in European data pro-
tection law. Yet, the role of Breyer in establishing the
meaning of identification and what it means to be an
identified natural person has remained unnoticed.
Davis has recently pointed out that the CJEU in
Breyer may have invalidated the understanding of iden-
tification as distinguishing or being distinguished from
a group, advanced by the Working Party. According to
Davis, the Breyer decision rules out a possibility of di-
rect identification by online identifiers (ie dynamic IP
address does not enable the plaintiff to be directly iden-
tified). The argument goes: since the Court does not
recognize Mr Breyer directly identified by his dynamic
IP address, while the very point of IP addresses is to dis-
tinguish one website visitor from another, the Court ef-
fectively endorses the narrowest understanding of
‘identified’ as ‘identified by name’ in the sense of estab-
lishing one’s civil identity.
Indeed, the Court, limiting
its considerations on what ‘identified’ means to one
paragraph, concluded that
it is common ground that a dynamic IP address does not
constitute information relating to an ‘identified natural
person’, since such an address does not directly reveal the
identity of the natural person who owns the computer from
which a website was accessed, or that of another person
who might use that computer.
With this conclusion the Court agreed with the referring
and followed the Advocate General:
[t]he person to which those particulars relate is not an
‘identified natural person’ [as they]... do not reveal, di-
rectly or immediately, the identity of the natural person
who owns the device used to access the website or the iden-
tity of the user operating the device (who could be any nat-
ural person).
This reading of Breyer effectively reduces the meaning
of identification and ‘identified’ to the look-up identifi-
cation, ie by means of identifiers connecting a person to
his/her real world identity. This narrow understanding
of identification therefore takes out of the protective
scope of the GDPR many data-driven practices which
have long been assumed to involve personal data proc-
essing and thus fall under the GDPR, but which are not
[43]; Lindqvist, [88]; and College van burgemeester en wethouders van
Rotterdam v M.E.E. Rijkeboer Case C-553/07 [2009] ECR I-3889,
ECLI:EU:C:2009:293 [59].
111 Lindqvist [24].
112 Rijkeboer [62].
113 Worten Equipamentos para o Lar SA v Autoridade para as Condic¸~
oes de
Trabalho (ACT) Case C-342/12 [2013] OJ C225/37, ECLI:EU:C:2013:355
[19], [22].
114 O
¨sterreichischer Rundfunk and Others [64].
115 Satakunnan Markkinapo¨rssi and Satamedia Case C-73/07 [2008] ECR I-
09831, ECLI:EU:C:2008:727 [35], [37].
116 The Court makes no distinction between identified and identifiable in its
treatment of the case: ‘The term [“identified or identifiable natural per-
son”] undoubtedly covers the name of a person in conjunction with his
telephone coordinates or information about his working conditions or
hobbies.’ [24].
117 On the one hand, the Court suggests that identification in the sense of
the Directive can be achieved also by non-name identifiers: ‘act of ...
identifying them by name or by other means, for instance by giving their
telephone number or information regarding their working conditions
and hobbies, constitutes ‘the processing of personal data’ [27]. On the
other hand, the Court directly states that the term ‘any information relat-
ing to an identified or identifiable natural person’ only covers the non-
name identifiers in conjunction with the name of a person [24].
118 YS and others and Nowak focusing on the meaning of “relating to” ele-
ment of the definition of personal data.
119 Scarlet v Sabam, Case C-70/10, ECLI:EU:C:2011:771 [51].
120 Eg Borgesius (n 35).
121 Davis (n 8) 17.
122 Breyer [38].
123 Breyer [24].
124 AG opinion in Breyer [56].
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tied to a real-world identity of an individual by his
phone number, address, passport number, a name or
similar. This includes but is not limited to online behav-
ioural advertising when the data processed does not in-
clude real-world identifiers and a person is ‘reached’
through the online identifiers alone, facial recognition
when the facial templates are not associated with the
real world identity, individual profiling targeted at a
person by means other than offline identifiers, and
many others. While in some cases, like in Breyer, it may
still be possible to argue that the data relates to a person
who is ‘identifiable’ even when the information neces-
sary for the real-world identification is not in the hands
of a controller but is ‘reasonably likely to be used’ for
the identification purposes nevertheless, it still does not
resolve the resulting gap in legal protection. Indeed,
while, as Borgesius correctly argued, the test of identifi-
ability does not require data subjects to be known by
there must still be a reasonably likely chance of
establishing that name or another real-world identifier.
In the end of the day, the concept of identifiability is a
‘possibility of’ identification and its meaning is derived
from the meaning of identification. If the latter means
real-world identification only, the former must include
the possibility of this real-world identification. The pos-
sibility to single one out in other ways is not sufficient.
Principle of effective and complete protection
and contextual reading of Breyer
Yet, the Breyer decision has to be read in light of the
aim of data protection law to ensure effective and com-
plete protection of data subjects
and thus should be
construed in such a way that it does not affect the valid-
ity of a broader understanding of identification as dis-
tinguishing from a group. This reading remedies any
restrictive effects on the scope of legal protection.
In order to do so recounting the facts of the case is
necessary. The following circumstances gave rise to the
case. The websites of the German Federal Government
institutions stored the website access logs after the web-
sites have been accessed, which included the name of the
web page or file accessed, search terms, the time of access,
the quantity of data transferred, whether or not access
was successful, and the IP address. Mr Breyer was one of
these websites’ visitors whose dynamic IP address was
retained. He challenged this retention practice in the
administrative courts, objecting—on the data protection
grounds—to the retention of the IP addresses, unless
such retention was necessary to restore the availability of
the websites after access failure.
The dispute in part
concerned whether or not the dynamic IP address consti-
tutes information relating to an identified or identifiable
person and thus is or is not personal data. The case went
to the court of appeal and finally to the Federal Court of
Justice which referred the case to the CJEU. The latter
ruled that the IP address does not relate to an identified
but to an identifiable natural person.
The key to the alternative interpretation with the effect
that an online identifier such as an IP address can iden-
tify a person rather than simply render him or her identi-
fiable is in reading the decision with close attention to
the context of the case. As the Working Party rightly
points out, the context defines whether or not a particu-
lar identifier is sufficient to identify a person.
In this
case, the dispute arose because of the data retention prac-
tices of the website owners ‘after the websites were
accessed and the browsing session ended. As the
Advocate General observes, ‘[t]he owners of web sites
that are accessed using dynamic IP addresses also tend to
keep records of which pages are accessed, when and from
which dynamic IP address. It is technically possible to re-
tain those records indefinitely after each user terminates
his Internet connection’.
Mr Breyer objected not to
the processing of the dynamic IP addresses per se, eg dur-
ing the browsing session, but to ‘storing, or arranging for
third parties to store, after consultation of the web-
[emphasis added]. Hence, the question of the re-
ferring court also concerned the status of the dynamic IP
addresses after consultation of the websites. The referring
court submitted that ‘the data stored does not enable Mr
Breyer to be directly identified. ... [and] [t]he operators
of the websites at issue in the main proceedings can iden-
tify Mr Breyer only if the information relating to his
identity is communicated to them by his internet service
[emphasis added]. The CJEU agreed.
However, this does not preclude a conclusion that a web-
site visitor is ‘identified’ by a dynamic IP address under
different circumstances, eg during the browsing session
and before the Internet connection is broken. Indeed,
when to identify someone means to distinguish that
someone from a group, to ‘zoom in’ on a flesh and blood
individual, and implies reaching a person, a website visi-
tor is identified, ie distinguished from other visitors by
125 Borgesius (n 5).
126 Google Spain [34], [53]; Unabha¨ngiges Landeszentrum fu¨r Datenschutz
Schleswig-Holstein v Wirtschaftsakademie Schleswig-Holstein GmbH
(Wirtschaftsakademie) Case C-210/16 [2018] (ECLI:EU:C:2018:388) [28]
and Jehovan todistajat Case C-25/17 [2018] (ECLI:EU:C:2018:551) [66].
127 Breyer [14]–[17].
128 ‘[T]he extent to which certain identifiers are sufficient to achieve identifi-
cation is something dependent on the context of the particular situation.’
(WP136 13).
129 AG opinion in Breyer [4].
130 Breyer [17].
131 Breyer [24].
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means of an IP address and is ‘reached’ by the website
owner in real time when presenting to that visitor the
website’s content using an IP address. The IP address
provides a direct link to a flesh and blood individual who
is browsing through the website’s content. Under these
circumstances, a website visitor is directly identified by
the dynamic IP address in the sense of session identifica-
tion. Once the session is ended and the Internet connec-
tion is broken, the retained dynamic IP address is no
longer pointing to a specific nod on the network. The di-
rect link with the visitor is severed and additional infor-
mation is necessary to restore it. This contextual reading
of Breyer does not effect the validity of the Working
Party’s understanding of identification as distinguishing
a person from the group and preserves a far reach of the
This contextual reading of Breyer is not only possible
as demonstrated above, but also necessary in light of the
emerging principle of effective and complete protection
of the data subject. The principle was first introduced by
the CJEU in Google Spain. The principle has been applied
since to prevent a narrow interpretation of the concept
of a controller and thus against restricting personal scope
of the data protection law which would go against the
aim to afford a data subject effective and complete pro-
As many scholars have argued,
the meaning
of identification should not be construed narrowly, eg re-
duced to the look-up identification, because a growing
body of invasive data processing practices, such as online
advertising, facial recognition, profiling and others, do
not have to and often do not rely on the name, address
or another real-world identifier. A narrow interpretation
of identification and what an ‘identified natural person
mean would take those practices and their effects out of
the scope of the data protection law and deprive the peo-
ple affected by them of the GDPR’s protection.
Identification as individuation in national case
The broad interpretation of identification proposed in
this article has support in some national case law.
Notably, in Vidal-Hall, a case concerning processing
browser-generated data and cookies by Google, the
Court of Appeal of England and Wales ruled that
‘[i]dentification for the purposes of data protection is
about data that “individuates” the individual, in the
sense that they are singled out and distinguished from
all others’.
Thereby the Court recognized recognition
identification and rejected a narrow interpretation of
identification as by name only: ‘It is immaterial that the
[browser-generated information] does not name the
user. The BGI singles them out and therefore directly
identifies them.’
For this reason the Court did not
find it necessary to consider whether or not the user is
‘identifiable’, following the Recital 26 test.
The same
‘individuation’ approach to identification was taken by
the English court in Bridges
(although not discussed
as relevant on appeal
). The case concerned testing of
a facial recognition system by the police where CCTV
cameras captured facial images of the passers-by within
the cameras’ range, and first distinguished human faces
and then distinguished one face from another, to enable
matching the images with biometric templates on the
watch lists. The claimant was in the range of the cam-
eras on two occasions and filed a complaint that, among
others, his personal data was processed unlawfully, even
though he was not matched with the watch list on any
occasion. According to the court, there are two routes
to argue that personal data is processed. The first route
is to be pursued when the data on its own does not
qualify as personal data, but additional information can
be obtained in future to enable identification. In this
case the Breyer reasoning is to be followed to establish if
identification is reasonably likely and if a natural person
to whom the data relates is identifiable.
The second
route is ‘to the effect that a person is sufficiently identi-
fied for the purpose of the definition of personal data if
the data “individuates” that person’.
The second
route was followed. The court found that processing of
the claimant’s image constituted processing of personal
data even prior to the matching of the facial images and
possible recognition “on the basis that the information
recorded by [the facial recognition system] individuates
him from all others, i.e. it singles him out and distin-
guishes him from all others.”
Since the facial images
by themselves directly identified the claimant, the court
considered further considerations of the possibility of
identification unnecessary.
The court effectively
132 Google Spain [34], [53] Wirtschaftsakademie and Jehovan todistajat.
133 Eg Leenes (n 18) and Nissenbaum (n 23).
134 Vidal-Hall v Google Inc [2015] EWCA Civ 311 from 114 et seq.
135 Ibid 115.
136 Ibid 124.
137 R (on the application of Edward Bridges) v The Chief Constable of South
Wales Police and Secretary of State for the Home Department [2019]
EWHC 2341 (Admin), 122–25.
138 R (on the Application of Bridges) v South Wales Police [2020] EWCA Civ
139 R (on the application of Edward Bridges) v The Chief Constable of South
Wales Police and Secretary of State for the Home Department [2019]
EWHC 2341 (Admin) at 116–17.
140 Ibid 119.
141 Ibid 122.
142 Bridges [123].
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recognized targeting identification as a type of identifica-
tion for the purposes of data protection law.
Conclusion: what this means for data
Despite its core role in the EU system of data protec-
tion, the notion of identification in the sense of the pro-
cess and the fact of being identified has been a neglected
subject both in data protection law and scholarship.
With the primary focus placed on the meaning of iden-
tifiability as a legally relevant possibility of identifica-
tion, it remained unclear the possibility of what exactly
is at issue. While Article 29 Working Party interpreted
identification broadly, as distinguishing one in a group,
this interpretation has been questioned in light of the
CJEU decision in Breyer, and the uncertainty as to the
meaning of identification remained.
This article reduces this uncertainty in two ways. First,
it offers an account of what constitutes identification out-
side of the legal context and proposes an integrated socio-
technical typology of identification as a process or result
of distinguishing a person in a group. Building on existing
socio-technical accounts of identification, the typology
distinguishes five identification types: (i) look-up or civil
identity identification where persistent identifiers such as a
name, passport or social security number, a phone num-
ber or address link to a person in a real world, (ii) recogni-
tion identification where a person is recognized as known
from a previous interaction by a token or another persis-
tent identifier that does not connect to the real-world civil
identity, (iii) session identification where a person is
reached or linked to an identifier of a limited lifetime for a
duration of one interaction, (iv) classification identifica-
tion where a person is identified as a member of a certain
existing group or category by displaying characteristics of
that group or category; and (v) targeting identification.
The typology has a temporal dimension, in a sense that
look-up, recognition and to a limited extent session iden-
tification are based on persistent identifiers that enable
longitudinal tracking, and classification and targeting
identification—if not done together with one of the other
types—are transient. The article distinguishes targeting
identification as a new identification type, ie selecting in a
single moment of time a particular individual from a
done either on the basis of a single unique identifier which
does not have to be persistent, or on the basis of a rich
datasetthatuniquelycharacterizes an individual. Evidence
from the literatures on calculated publics, profiling in
recommender systems, price and content personalization
strongly suggests that targeting as a mode of identification
might gain in popularity.
Finally, the article clarifies the legal meaning of iden-
tification under the GDPR. If identification—as the
Article 29 Working Party would have it—means distin-
guishing from a group, it unconditionally encompasses
the look-up, recognition, session, and targeting types of
identification, because they enable reaching, or zooming
in on a flesh and blood individual. Whether or not that
person is known by name is immaterial. Whether or not
classification is identification in the GDPR sense is
context-sensitive. Classification only constitutes identi-
fication where in a given context, eg a timeframe, a lim-
ited space or a group of people, a group characteristic
that is otherwise not unique is distinguishing a person
as unique in a sample. While the CJEU in Breyer seems
to have invalidated this approach in favour of name-
based identification only, I argue for a contextual inter-
pretation of the decision, which is consistent with the
Working Party’s position. Such interpretation negates
Breyer’s restrictive potential and does not exclude any of
the identification types from the scope of the GDPR.
This has significant implications for data protection
law, both short-term on the practical level as well as
long-term on the more principal level. Without an ambi-
tion of being comprehensive, let me first sketch some il-
lustrative short-term practical consequences. The
primary consequence is that the broad interpretation of
identification naturally widens the GDPR material scope
and leads to a broad application of the GDPR, granting
GDPR protections also in the situations where the data
subjects are not identified by their civil identities, yet still
affected. This includes more conventional cases of identi-
fication such as recognition or session identification rou-
tinely practiced on the web, but also